The present invention relates to a method and a device for monitoring or safeguarding a machine having a first machine part that carries out a working movement towards a second machine part in order to machine a workpiece. More particularly, the invention relates to a method and a device for monitoring and safeguarding a bending press, press brake, stamping machine, or cutting machine, although it is not restricted thereto and can likewise be used in other machines.
Bending or folding is a known method for machining workpieces. Machining of the workpiece essentially takes place in that a tool is pressed against a matrix. The intermediate space between the tool and the matrix is typically monitored by an optical camera-based protective system during the downward travel of the tool, in order to prevent body parts of the operator from entering the opening gap between the tool and the matrix while the machine is running.
In such camera-based protective systems, a protective zone is typically monitored between the tool and the matrix, which protective zone is reduced during the downward travel in the vertical direction to avoid an unintentional safety shutdown. During the reduction and/or deactivation of the protective zone, which takes place step-by-step, however, an overrun travel of the tool has to be safeguarded in order to ensure the required safety of the operator. The motion speed of the tool is therefore typically decelerated in the region of the workpiece, in order to reduce a corresponding overrun travel and to ensure the safety of the operator. Since the reduced motion speed during the downward travel of the tool reduces the general productivity of the machine, however, the corresponding braking procedure is desired to be initiated as late as possible.
In order to ensure the reduced motion speed of the tool, the position of the tool is usually cyclically acquired from incremental encoders and processed in a separate processor. In a following processing cycle, the position and process data thus ascertained are then output to a control module, which shuts down the movement of the tool in the event of respective deviations.